Learn how to make holes on a surface
In Fusion, creating accurately aligned counterbore holes on a curved overmold by using the Hole Command can be difficult. This write-up explains the process of projecting the existing tapped-hole axes onto the surface, adding 3D points where the geometry intersects, and placing each point on a plane along its axis. The Hole command then follows the sketch plane’s Z direction, aligning each hole with the matching tapped hole in the main body.
Create axes from the existing tapped holes
The example uses an overmold that curves in multiple directions and a main body with existing tapped holes. To start, turn off the overmold and use Axis Through Cylinder on each tapped hole. Repeat the command for the other holes, then extend the axes if they need more height.
Turn the overmold back on to check that the axes pass through it. Placing a Hole directly on the curved face is not precise: you can drag the hole around, but it won’t snap to the underlying axis, and its center may be off.
Project the axes onto the curved surface
A first idea is to project each existing hole onto the overmold with Project to Surface. This creates a curve on the curved face, but the Hole command cannot find a usable center point: the projected circle lies on the curved surface, so it is not a flat circle with a center the command can snap to.
Instead, create a sketch on the front face, then choose Create > Project > Project to Surface. Select the curved overmold face and an existing axis as the curve to project. The projection type can be Closest Point or Along Vector. In this example, Along Vector is easier to see: choose an axis for the projection direction, and Fusion projects the top and bottom of that axis onto the curved face.
You can select all four curves in the same operation. Fusion allows multiple selections when the command field is labeled “faces” or “curves.” The result is projected geometry that follows the surface, but it still needs a point for the Hole command.
Add a 3D point at each intersection
Create a separate sketch on a side face and use Include 3D Geometry to project the axis lines. This projection must be a separate step from projecting the axes onto the curved surface. The two sets of geometry now intersect, but Fusion still needs an actual point at each intersection.
Turn on 3D Sketch, choose the Point command, and snap to an intersection. The point must be in the right location and have the right direction for the Hole command.
Why the offset plane fails
An offset plane above the part can help demonstrate the location step. With 3D Sketch on, you can create a point at the intersection. But that sketch plane is horizontal, so its Z direction points up and down. The Hole command uses the sketch direction for its Z-axis, and its dialog does not provide a separate way to set the hole direction.
Align the sketch plane with each axis
Undo the offset-plane setup. Instead, create a Plane Along Path on the axis. The plane’s position along the axis does not matter. Create a sketch on that plane, keep 3D Sketch turned on, and place a point at the intersection of the projected geometry.
Now the sketch plane’s Z direction follows the axis.
Create the M6 counterbore and limit the cut
Choose the Hole command and select the point. The counterbore now has the correct location and orientation. Set it to a metric M6 counterbore, then expand Objects to Cut and uncheck the main body so the hole cuts only the overmold.
A counterbore on a curved surface can leave a small extra face. Click and hold on the face, move through the face choices until the extra face is selected, then press Delete.
Repeat the setup for the other three holes
Each axis has a different orientation, so create a Plane Along Path for each one. Add a sketch and 3D point at the intersection, then use the Hole command. Fusion remembers the Hole settings, but check that the main body is not included in Objects to Cut.
After creating the remaining holes, hold Control to select the extra faces together and press Delete. Turn off the sketches and construction geometry to view the finished holes.
The construction steps creates the needed precision
This workflow takes several steps because the design needs to store both the exact hole locations and their directions. This is much more precise than just clicking on the surface.
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